Control for refrigerating apparatus



Nov. 20, 1962 J. H. HEIDORN 3,064,447

CONTROL FOR REFRIGERATING APPARATUS Filed Nov. 16, 1959 INVENTOR. John H. Heidorn His A flornev trite rates l stens 3,54,447 Patented Nov. 29, 1952 3 964 447 corsrnot non nnrinohnarnvo APPARATUS Sohn H. Heidorn, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Filed Nov. 16, 1959, Ser. No. 853,127 12 Claims. (Cl. 62-197) This invention relates to refrigerating apparatus and more particularly to an improved control arrangement for use in automobile air conditioning systems and the like.

It is now customary practice to drive the refrigerant compressor of an automobile air conditioning system by means of the car engine. Since the speed of the car engine varies widely without any regard for refrigeration requirements, it becomes necessary to provide some means for compensating for the wide variation in the compressor speed.

it is an object of this invention to provide an inexpensive and trouble-free control which compensates for variations in the compressor speed and which reduces the horsepower required for operating the compressor at high engine speeds.

Another object of this invention is to provide an improved control arrangement which includes means for returning liquid refrigerant and oil from the evaporator to the compressor so as to provide cooling and lubrication for the compressor at high compressor speeds.

Still another object of this invention is to provide for the return of liquid refrigerant to the compressor in such a manner that as the back pressure drops and the quantity of gas returned to the compressor decreases with the resultant higher compression ratios and heat, the amount of liquid refrigerant returned to the compressor increases so as to provide increased compressor cooling.

it 18 another object of this invention to provide a system in which bypassed liquid normally aids in maintaining pressures on the compressor seal above atmospheric pressure in the normal operating ambient temperatures.

Still another object of this invention is to provide an improved control arrangement for use in automobile air conditioning systems which prevents damage to components of the system resulting by refrigerant leaks by preventing excessive high temperatures of the discharge gases in a faulty system.

Further objects and advantages of the present invention will be apparent from the following description, ref erence being had to the accompanying drawing wherein a preferred embodiment of the present invention is clearly shown.

In the drawing:

FiGURE 1 is a vertical sectional view of a control valve schematically showing the refrigerant connections to the valve.

FEGURE 2 is a sectional view taken on line 22 of FIGURE 1.

FIGURE 3 is a fragmentary sectional view showing the bypass valve piston arranged to throttle gas flowing in the suction line.

Referring now to the drawing wherein a preferred embodiment of the invention has been shown, reference numeral 2% generally designates a refrigerant compressor of the type which is adapted to be driven from an internal combustion engine 12. The engine 12 is intended to designate a conventional automobile engine of the type which is used to drive a passenger automobile or the like and which therefore is required to operate at widely varying speeds without any regard for refrigeration requirements.

The compressor 18: discharges compressed refrigerant into a condenser 14 from whence the liquid refrigerant is fed into a receiver 16. Liquid is fed from a point adjacent the bottom portion of the receiver 16 to an evaporator 18 through a liquid line 29 in which there is provided a conventional pressure reducing device 22. The

ressure reducing device 22 could be in the form of an automatic expansion valve, a thermostatic expansion valve or a capillary tube type restrictor. The vaporized refrigerant leaves the evaporator 13 through a suction line as in which a control valve, generally designated by the reference numeral 26, is located.

The refrigerant vapor returning to the compressor from the evaporator enters the valve 26 through an inlet passage 28 and leaves the valve through an outlet passage 3i which is connected to the inlet or" the compressor 10. A small capillary tube 32 is provided as shown and serves to convey a small amount of liquid refrigerant from a point adjacent the inlet of the evaporator 18 to the suction return passage 30. Since both ends of the capillary passage 32 are maintained at nearly the same pressure during normal operation of the refrigerating system, it is apparent that very little liquid refrigerant will flow through the capillary passage 32 but in the event the valve 26 serves to throttle the flow of refrigerant from the evaporator to the inlet of the compressor, an increased amount of liquid refrigerant would flow through the capillary passage 32. The valve 26 includes a bypass valve piston element 4t) which is normally biased into its uppermost position, as viewed in FIGURE 1, by means of a coil spring 42.

Whenever the compressor 16 operates at excessively high speeds, there will be a resulting reduction in the evaporator pressure and if this becomes excessive, it will cause frost to form on the evaporator. In order to prevent such frost formation, the main body of the valve 26 is provided with an internal passage 44 which leads from the inlet passage 28 to the diaphragm chamber 4-6. A diaphragm is mounted in the chamber 46 is adapted to be actuated in response to changes in pressure in the suction line. A spring normally biases the diaphragm in the downward position, as viewed in FIGURE 1. The amount of pressure exerted by the spring 5%) can be adjusted by means of the cam lever 52 which is adapted to be operated manually by means of a Bowden wire 54 or any similar manually operated adjusting means. The cam lever 52 is provided with a cam surface 56 which acts against the upper side of a plate 53 held adjacent the upper end of the spring 56. An adjustable stop 60 is provided as shown for adjusting the minimum spring ressure exerted by the spring 5% so that under no circumstances will the pressure in the evaporator be allowed to go low enough to cause freezing of the condensate on the evaporator. Thus, when the adjustable stop so is screwed downwardly, it will increase the pressure against the upper end or" the spring 5 5. The spring Si is supported in a housing 62 which encloses the upper end of the diaphragm chamber 46. The upper wall 64 of the housing 62 is flexible so as to allow for adjustment of the spring pressure. A pilot valve 723 has its one end arranged in engagement with the diaphragm 48 and has its other end arranged in engagement with a spring 72 which biases a pilot valve into the closed position in which it is shown in FIGURE 1.

When the pressure within the diaphragm chamber 46 falls below a predetermined value, the pilot valve 7 will be moved downwardly, as viewed in FIGURE 1, so as to occupy a position similar to that in which it is shown in FlGURE 3, whereby a quantity of high pressure refrigerant is admitted into the space 74 above the bypass valve piston iii. As shown in FIGURE 1 of the drawing, the liquid refrigerant for this purpose is taken from the bottom portion of the receiver 16 by means of a conduit 76 with the result that the liquid refrigerant will be at a rei atively high pressure and will tend to include any oil which may have accumulated in the bottom portion of the receiver 16. This conduit 76 connects with a passage 73 in the valve body 2s which conveys the liquid into the chamber 80. When the pilot valve 74} moves to the open position, this liquid flows past the pilot valve and through ports 82 formed in the pilot valve guide element 8 -2. The stationary element 88 which serves as a support for the spring 72 is provided with axially extending passages 90 which convey the liquid into the chambers 74 above the bypass valve piston 40. The high pressure liquid acting on the upper end of the piston 48 serves to move the piston 46 against the action of the spring 42 an amount depending upon the pressure of the liquid supplied through the line 76.

It will be noted that the bypass valve piston 40 is provided with circumferentially extending spiral groove 10% which allows a limited amount of the liquid to pass therethrough. The depth of the groove 100 is greatest at the upper end of the piston 46 and gradually becomes shallower towards the lower end. As the piston 40' moves from the position in which it is shown in FIGURE 1 to the position in which it is shown in FIGURE 3, the length of travel and the restriction to the flow of the liquid refrigerant through the groove 1% will be reduced with the result that the flow of liquid refrigerant through the groove 100 will increase as the piston 40 moves down. In this .manner, excessive high head pressures, such as occur at excessive compressor speeds, will cause a greater amount of liquid refrigerant to bypass the evaporator 18 and to enter the suction line leading to the compressor so as to serve the dual purpose of cooling the compressor and returning an increased amount of lubricant to the compressor. Also, when the piston element 40 moves from the position in which it is shown in FIGURE 3, it will serve to throttle the main suction line passage through the valve 26 so as to reduce the horsepower required to operate the compressor at these high compressor speeds.

For purposes of illustration the valve 26 has been shown as separate from the expansion valve 22 whereas in actual practice these valves could be combined into a single casting so as to reduce the number of parts and eliminate the need for connecting lines.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. In combination, a compressor, a condenser, a receiver, a pressure reducing means, an evaporator, conduit means connecting said compressor, condenser, receiver, pressure reducing means, and said evaporator in series refrigerant flow relationship, a control valve located in said conduit means between the outlet of said evaporator and the inlet of said compressor, said valve including means for throttling the flow of refrigerant from said evaporator into said compressor, means responsive to a predetermined decrease in the pressure in said evaporator for operating said throttling means so as to reduce the flow of refrigerant in said conduit, and means for supplying liquid refrigerant from said receiver to the inlet of said compressor when the pressure in the conduit means between said evaporator and said compressor falls below a predetermined value.

2. In combination, a compressor, a condenser, a receiver, a pressure reducing means, an evaporator, conduit means connecting said compressor, condenser, receiver, pressure reducing means, and said evaporator in series refrigerant flow relationship, a control valve located in said conduit means between the outlet of said evaporator and the inlet of said compressor, said valve including means for throttling the flow of refrigerant from said evaporator into said compressor, means responsive to a predetermined decrease in the pressure in said evaporator for operating said throttling means so as to reduce the flow of ease? 4 refrigerant in said conduit, and means forming a capillary passage leading from the outlet of said pressure reducing means to the outlet of said control valve for bypassing said a evaporator and said throttling means.

3. in combination, a compressor, a condenser, a receiver, a pressure reducing means, an evaporator, conduit means connecting said compressor, condenser, receiver, pressure reducing means, and said evaporator, in series refrigerant flow relationship, a control valve located in said conduit means between the outlet of said evaporator and the inlet of said compressor, said valve including a refrigerant passage therein and a piston movable into said passage for throttling the flow of refrigerant from said evaporator into said compressor, means responsive to a predetermined decrease in the pressure in said evaporator for operating said piston so as to reduce the flow of refrigerant in said conduit, and means for supplying liquid refrigerant from said receiver to the inlet of said compressor when the pressure in the conduit means between said evaporator and said compressor falls below a predetermined value.

4. In combination, a compressor, a condenser, a receiver, a pressure reducing means, an evaporator, conduit means connecting said compressor, condenser, receiver, pressure reducing means, and said evaporator in series refrigerant flow relationship, a control valve located in said conduit means between the outlet of said evaporator and the inlet of said compressor, said valve including a refrigerant passage therein and a piston movable into said passage for throttling the flow of refrigerant from said evaporator into said compressor, means responsive to a predetermined decrease in the pressure in said evaporator for operating said piston so as to reduce the flow of refrigerant in said conduit, and means for supplying liquid refrigerant from said receiver to the inlet of said compressor when the pressure in the conduit means between said evaporator and said compressor falls below a predetermined value, said last named means including means whereby the quantity of liquid refrigerant supplied is controlled by said piston.

5. A refrigerating system comprising in combination; a compressor, a condenser, a receiver, and an evaporator connected in series refrigerant flow relationship; a control valve connected between the outlet of said evaporator and the inletof said compressor; said valve including means responsive to the pressure at the inlet of said compressor for throttling the flow of refrigerant vapor from said evaporator into said compressor in response to a predetermined decrease in pressure within said evaporator; and means for supplying liquid refrigerant to the inlet of said compressor in response to a predetermined reduction of pressure within said evaporator.

6. A refrigerating system comprising in combination; a compressor, a condenser, a receiver, and an evaporator connected in series refrigerant flow relationship; a control valve connected between the outlet of said evaporator and the inlet of said compressor; said valve including means responsive to the pressure at the inlet of said compressor for throttling the flow of refrigerant vapor from said evaporator into said compressor in response to a predetermined decrease in pressure within said evaporator; and means for supplying liquid refrigerant to the inlet of said compressor in response to a predetermined reduction of pressure within said evaporator, said last named means serving to increase the amount of liquid refrigerant supplied to the. inlet of said compressor as the flow of refrigerant vapor from said evaporator to said compressor is throttled.

7. A refrigerating system comprising in combination; a compressor, a condenser, a receiver, and an evaporator connected in series refrigerant flow relationship; a bypass conduit for supplying liquid refrigerant from said receiver to the inlet of said compressor; a control valve means having a first passage for refrigerant vapor flowing between the outlet of said evaporator and the inlet of said compressor and having a second passage for said refrigerant liquid flowing from said receiver to the inlet of said compressor; said control valve means including a first means responsive to the pressure in said evaporator for throttling the flow of refrigerant from said evaporator into said compressor in response to a predetermined decrease in evaporator pressure, and a second means for controlling the supply of liquid refrigerant from said receiver to the inlet of said compressor.

8. Valve means operable to control the flow of refrigerant through the evaporator of a refrigeration system of the type having a compressor, condenser and a pressure reducing means in series flow circuit with the evaporator, comprising a valve body having two intercommunicating passages, the first of which is adapted for connection with the outlet of the evaporator and the second of which is adapted for connection with the inlet of the compressor, a pressure operated diaphragm enclosed in said valve body, a pilot valve member actuated by said diaphragm, means responsive to opening of said pilot valve operable to restrict communication between said passages, passage means establishing communication between one side of said diaphragm and said first passage, and means forming a liquid refrigerant bypass establishing communication between the outlet of said condenser and said second passage.

9. Valve means operable to control the flow of refrigerant through the evaporator of a refrigeration system of the type having a compressor, condenser and a pressure reducing means in series flow circuit with the evaporator, comprising a valve body having two inter communicating passages, the first of which is adapted for connection with the outlet of the evaporator and the second of which is adapted for connection with the inlet of the compressor, a pressure operated diaphragm enclosed in said valve body, a pilotvalve member actuated by said diaphragm, means responsive to opening of said pilot valve operable to restrict communication between said passages, passage means establishing communication between one side of said diaphragm and said first passage, means forming a liquid refrigerant bypass establishing communication between the outlet of said condenser and said second passage, and means for adjusting the pressure at which said diaphragm opens said pilot valve.

10. Valve means operable to control the flow of refrigerant through the evaporator of a refrigeration system of the type having a compressor, condenser and a pressure reducing means in series flow circuit with the evaporator, comprising a valve body having two intercommunicating passages, the first of which is adapted for connection with the outlet of the evaporator and the second of which is adapted for connection with the inlet of the compressor, a pressure operated diaphragm enclosed in said valve body, a pilot valve member actuated by said diaphragm, means responsive to opening of said pilot valve operable to restrict communication between said passages, passage means establishing communication between one side of said diaphragm and said first passage, and means forming a liquid refrigerant bypass establishing communication between the outlet of said condenser and said second passage, said last narned means comprising means for varying the flow through said bypass in response to changes in said restriction.

11. A refrigeration system comprising in combination, a compressor, an evaporator, a condenser, and a pressure reducing means connected in series flow relationship, said system including a valve body having two intercommunicating passages, a first of which is adapted for connection with the outlet of the evaporator and the second of which is adapted for connection with the inlet of the compressor, a pressure operated diaphragm enclosed in said valve body and having one side subjected to the pressure in said first passage, a pilot valve member operated by said diaphragm, a main valve including a piston arranged to restrict communication between said passages, means establishing communication between one side of said diaphragm and said first passage, and means establishing communication between the outlet of said condenser and said second passage for supplying liquid refrigerant to the inlet of the compressor, said last named means including a spiral groove surrounding said piston and arranged to be progressively uncovered by movement of said piston.

12. In combination, a compressor, a condenser, a pressure reducing means, an evaporator, conduit means connecting said compressor, condenser, pressure reducing means and said evaporator in series refrigerant and lubricant flow relationship, a control valve located in said conduit means between the outlet of said evaporator and the inlet of said compressor, said valve including a passage therein and a control means for throttling the flow from said evaporator to said compressor, means responsive to a predetermined decrease in the pressure in said evaporator for operating said control means so as to reduce the flow in said conduit, and means for returning lubricant to said compressor when said control means throttles the flow of fluid from said evaporator to said compressor including means for bypassing said control means.

References Cited in the file of this patent UNITED STATES PATENTS 2,363,273 Waterfill Nov. 21, 1944 2,573,684 Binder Nov. 6, 1951 2,734,346 Dickieson Feb. 14, 1956 2,779,162 Baker et a1. Jan. 29, 1957 2,949,128 Carter Aug. 16, 1960 

